Short circuit: Quick workouts = fast results?

Have you ever spent half an hour pouring sweat from a Stairmaster, only to discover that you had burned just 300 calories– not nearly enough to undo the damage from a recent hot fudge sundae? Well, if the startling claims of a new gym are true, you could be burning up to triple that number of calories– without ever feeling sore.

According to the membership and publicity materials of Ladies Workout Express, which opened in July in the Rivanna Ridge Shopping Center on Pantops, an average woman can burn a whopping 600 to 900 calories during the gym's special 30-minute interval training workout. That's less time than it takes to watch an episode of Friends, but it may not be as easy.

Gaesser, a professor of exercise physiology and author of several fitness books including The Spark: The Revolutionary New Plan to Get Fit and Lose Weight 10 Minutes at a Time, says there's no way the center's claim can be true.

"King Kong, Godzilla, other mammals that are extinct? Perhaps," he says. "But no human on this planet is burning 1,800 calories in an hour."

Gaesser says that burning 900 calories in half an hour is the rough equivalent of running a record-breaking three-and-a-half minute mile– for nine miles.

"I've gotten letters," she says, "from male triathletes saying, 'You have no right to be making claims like this.'" But she's not deterred. Nor is her company. She says Ladies Workout Express, which has nearly 600 locations worldwide, is growing at the rate of 80 new franchises per month– a successful venture, by any measure.

But is its calorie claim really possible, or is it marketing hype designed to draw in an ever-fattening public?

"We have the ability to prove beyond the shadow of a doubt," Whedon insists, "that you can burn beyond 600 calories in half an hour."

That proof, she says, lies in the "Polar Heart Rate Monitor." (And she just happens to sell them.) She claims the Polar– which calculates the burn using a person's height, weight, and age– is accurate to within one beat of a hospital's EKG machine.

Whedon says that customers without the Polar typically burn 250 to 400 calories. With the Polar, the over 600-calorie burns begin appearing. "People are absolutely shocked," she says.

The workout at Ladies Workout Express consists of 24 "stations," alternating between weight machines and aerobic exercises– including a mini-trampoline and a two-step stair. Over lively music, a man's recorded voice gives cues about interval times.

The workout is similar to that of another new local gym, Curves, which opened in May on Angus Road. Curves owner Sandy Moore, a former nurse, says her company– which has thousands of locations worldwide– does not make similar calorie burning claims.

"The harder and faster you use each machine," Moore tells clients, "the more you'll get out of the workout."

Whedon says that Curves can't make the same claim because, without a Polar monitor and its built-in alarm, exercisers must occasionally stop to check their heart rates. Moore confirms this but says it makes no appreciable calorie difference.

At Ladies Workout Express, says Whedon, women are told to keep their heart rates alternating between 65 and 85 percent of their maximum heart rate without ever letting it fall below the lower end of the heart-rate range. That's where the Polar's alarm comes in; it lets exercisers know when they have gone below or above that rate. Such up and down heart rates, Whedon claims, force the heart to work twice as hard, thus burning twice as many calories.

In addition, Whedon says, the club's use of hydraulic machines, which use air pressure instead of traditional weights, delivers more workout in less time. (Curves uses similar hydraulic machines.)

Each machine works two opposing muscle groups. For instance, the bicep machine works the bicep on the way up, but then also works the tricep on the way down, taking care of two exercises in the time it might usually take to do one. As an added bonus, says Whedon, hydraulic machines don't break down muscle fiber like traditional weights, so users don't get sore.

In response to Whedon's detailed explanations, Gaesser laughs. "That's absurd," he says. "That woman needs to take a course in exercise science."

There are scientific limitations to calorie burning, he says. "People have a maximum rate of energy expenditure," says Gaesser. "That's something you can't change within the course of a workout."

Whatever the number of calories burned per workout, local Ladies Workout Express franchise owner Amy Silverman says her members are achieving excellent results. Without much advertising, she's attracted more than 300 members in just three months, a fact she attributes to the gym's all-women membership, convenient location, and to the appeal of a speedy results-oriented workout.

"I was looking for something simple and with reasonable hours," says Theresa Whiting, 40, a mother who also sells Mary Kay cosmetics. Although she admits she wonders about the calorie-burning claims, Whiting joined Ladies Workout Express a month ago and after working out three to six times a week for 30 minutes a session she has already shed seven and a half inches. She says the majority of women she knows who work out there have slimmed down.

Judy Cheape is another fan of the new gym. "I love it!" she exclaims.

In the past three months, Cheape says, she's dropped six pounds and more than nine inches– without dieting. She's encouraged seven women from her office to join, and she says they're also seeing great results.

Even debunker Gaesser says he doesn't mean to discourage people from joining Ladies Workout Express.

"Interval training is a great way to train for cardiovascular fitness," he says. "I'm fully behind that. It's just not going to burn the calories the way these people are hyping it."